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Refactor current_lock_owner
* src/filelock.c (current_lock_owner): Refactor to make further changes easier. This should not affect behavior.
This commit is contained in:
Paul Eggert
parent
4b6b9a7acd
commit
775fa8443f
1 changed files with 93 additions and 88 deletions
181
src/filelock.c
181
src/filelock.c
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@ -386,9 +386,6 @@ static int
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current_lock_owner (lock_info_type *owner, Lisp_Object lfname)
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{
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lock_info_type local_owner;
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ptrdiff_t lfinfolen;
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intmax_t pid, boot_time;
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char *at, *dot, *lfinfo_end;
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/* Even if the caller doesn't want the owner info, we still have to
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read it to determine return value. */
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@ -396,104 +393,112 @@ current_lock_owner (lock_info_type *owner, Lisp_Object lfname)
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owner = &local_owner;
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/* If nonexistent lock file, all is well; otherwise, got strange error. */
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lfinfolen = read_lock_data (SSDATA (lfname), owner->user);
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ptrdiff_t lfinfolen = read_lock_data (SSDATA (lfname), owner->user);
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if (lfinfolen < 0)
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return errno == ENOENT || errno == ENOTDIR ? 0 : errno;
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if (MAX_LFINFO < lfinfolen)
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return ENAMETOOLONG;
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owner->user[lfinfolen] = 0;
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/* Parse USER@HOST.PID:BOOT_TIME. If can't parse, return EINVAL. */
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/* The USER is everything before the last @. */
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owner->at = at = memrchr (owner->user, '@', lfinfolen);
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if (!at)
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return EINVAL;
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owner->dot = dot = strrchr (at, '.');
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if (!dot)
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return EINVAL;
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/* The PID is everything from the last '.' to the ':' or equivalent. */
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if (! integer_prefixed (dot + 1))
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return EINVAL;
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errno = 0;
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pid = strtoimax (dot + 1, &owner->colon, 10);
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if (errno == ERANGE)
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pid = -1;
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/* After the ':' or equivalent, if there is one, comes the boot time. */
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char *boot = owner->colon + 1;
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switch (owner->colon[0])
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/* Examine lock file contents. */
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if (true)
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{
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case 0:
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boot_time = 0;
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lfinfo_end = owner->colon;
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break;
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if (MAX_LFINFO < lfinfolen)
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return ENAMETOOLONG;
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owner->user[lfinfolen] = 0;
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case '\357':
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/* Treat "\357\200\242" (U+F022 in UTF-8) as if it were ":" (Bug#24656).
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This works around a bug in the Linux CIFS kernel client, which can
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mistakenly transliterate ':' to U+F022 in symlink contents.
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See <https://bugzilla.redhat.com/show_bug.cgi?id=1384153>. */
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if (! (boot[0] == '\200' && boot[1] == '\242'))
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/* Parse USER@HOST.PID:BOOT_TIME. If can't parse, return EINVAL. */
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/* The USER is everything before the last @. */
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char *at = memrchr (owner->user, '@', lfinfolen);
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if (!at)
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return EINVAL;
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boot += 2;
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FALLTHROUGH;
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case ':':
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if (! integer_prefixed (boot))
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owner->at = at;
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char *dot = strrchr (at, '.');
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if (!dot)
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return EINVAL;
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boot_time = strtoimax (boot, &lfinfo_end, 10);
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break;
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owner->dot = dot;
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default:
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return EINVAL;
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}
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if (lfinfo_end != owner->user + lfinfolen)
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return EINVAL;
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/* The PID is everything from the last '.' to the ':' or equivalent. */
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if (! integer_prefixed (dot + 1))
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return EINVAL;
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errno = 0;
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intmax_t pid = strtoimax (dot + 1, &owner->colon, 10);
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if (errno == ERANGE)
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pid = -1;
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char *linkhost = at + 1;
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ptrdiff_t linkhostlen = dot - linkhost;
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Lisp_Object system_name = Fsystem_name ();
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/* If `system-name' returns nil, that means we're in a
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--no-build-details Emacs, and the name part of the link (e.g.,
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.#test.txt -> larsi@.118961:1646577954) is an empty string. */
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bool on_current_host;
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if (NILP (system_name))
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on_current_host = linkhostlen == 0;
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else
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{
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on_current_host = linkhostlen == SBYTES (system_name);
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if (on_current_host)
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/* After the ':' or equivalent, if there is one, comes the boot time. */
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intmax_t boot_time;
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char *boot = owner->colon + 1, *lfinfo_end;
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switch (owner->colon[0])
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{
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/* Protect against the extremely unlikely case of the host
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name containing '@'. */
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char *sysname = SSDATA (system_name);
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for (ptrdiff_t i = 0; i < linkhostlen; i++)
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if (linkhost[i] != (sysname[i] == '@' ? '-' : sysname[i]))
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{
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on_current_host = false;
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break;
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}
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case 0:
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boot_time = 0;
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lfinfo_end = owner->colon;
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break;
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case '\357':
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/* Treat "\357\200\242" (U+F022 in UTF-8) like ":" (Bug#24656).
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This works around a bug in the Linux CIFS kernel client, which can
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mistakenly transliterate ':' to U+F022 in symlink contents.
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See <https://bugzilla.redhat.com/show_bug.cgi?id=1384153>. */
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if (! (boot[0] == '\200' && boot[1] == '\242'))
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return EINVAL;
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boot += 2;
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FALLTHROUGH;
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case ':':
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if (! integer_prefixed (boot))
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return EINVAL;
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boot_time = strtoimax (boot, &lfinfo_end, 10);
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break;
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default:
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return EINVAL;
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}
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}
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if (on_current_host)
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{
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if (pid == getpid ())
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return I_OWN_IT;
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else if (VALID_PROCESS_ID (pid)
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&& (kill (pid, 0) >= 0 || errno == EPERM)
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&& (boot_time == 0
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|| within_one_second (boot_time, get_boot_sec ())))
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return ANOTHER_OWNS_IT;
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/* The owner process is dead or has a strange pid, so try to
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zap the lockfile. */
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if (lfinfo_end != owner->user + lfinfolen)
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return EINVAL;
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char *linkhost = at + 1;
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ptrdiff_t linkhostlen = dot - linkhost;
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Lisp_Object system_name = Fsystem_name ();
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/* If `system-name' returns nil, that means we're in a
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--no-build-details Emacs, and the name part of the link (e.g.,
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.#test.txt -> larsi@.118961:1646577954) is an empty string. */
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bool on_current_host;
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if (NILP (system_name))
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on_current_host = linkhostlen == 0;
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else
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return emacs_unlink (SSDATA (lfname)) < 0 ? errno : 0;
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}
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else
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{ /* If we wanted to support the check for stale locks on remote machines,
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here's where we'd do it. */
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return ANOTHER_OWNS_IT;
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{
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on_current_host = linkhostlen == SBYTES (system_name);
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if (on_current_host)
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{
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/* Protect against the extremely unlikely case of the host
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name containing '@'. */
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char *sysname = SSDATA (system_name);
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for (ptrdiff_t i = 0; i < linkhostlen; i++)
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if (linkhost[i] != (sysname[i] == '@' ? '-' : sysname[i]))
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{
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on_current_host = false;
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break;
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}
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}
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}
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if (!on_current_host)
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{
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/* Not on current host. If we wanted to support the check for
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stale locks on remote machines, here's where we'd do it. */
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return ANOTHER_OWNS_IT;
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}
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if (pid == getpid ())
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return I_OWN_IT;
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if (VALID_PROCESS_ID (pid)
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&& ! (kill (pid, 0) < 0 && errno != EPERM)
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&& (boot_time == 0
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|| within_one_second (boot_time, get_boot_sec ())))
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return ANOTHER_OWNS_IT;
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}
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/* The owner process is dead or has a strange pid.
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Try to zap the lockfile. */
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return emacs_unlink (SSDATA (lfname)) < 0 ? errno : 0;
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}
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